Disclosed is an image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is sensed by the document feeding unit to thereby read an image on the document. The apparatus includes a photoelectronic converter for outputting an electric signal that conforms to amount of incident light, and a reading position setting unit for moving the document reading unit, irradiating the feed roller with light from the light source at each position to which the document reading unit is moved, causing the photoelectronic converter to output an electric signal that conforms to amount of light reflected from the feed roller at each position, detecting a range in a sub-scan direction over which this electric signal exceeds a predetermined threshold value, and setting a position at the center of this range as a reading position.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is sensed by the document reading unit to thereby read an image on the document, said apparatus comprising: a photoelectronic converter for outputting an electric signal that conforms to amount of incident light; and a reading position setting unit adapted to move the document reading unit, irradiate the feed roller with light from the light source at each position to which the document reading unit is moved, cause said photoelectronic converter to output an electric signal that conforms to amount of light reflected from the feed roller at each position, detect a range in a sub-scan direction over which this electric signal exceeds a predetermined threshold value, and set a position at the center of this range as a reading position.
2. The apparatus according to claim 1 , wherein said reading position setting unit decides the threshold value based upon a maximum value of the electric signal output by said photoelectronic converter.
3. The apparatus according to claim 2 , wherein said reading position setting unit adopts a value, which is obtained by multiplying the maximum value of the electric signal output by said photoelectronic converter by a predetermined coefficient, as the threshold value.
4. The apparatus according to claim 2 , wherein said reading position setting unit decides the threshold value based upon the maximum value of the electric signal, which is output by said photoelectronic converter, when said maximum value is greater than a predetermined value.
5. The apparatus according to claim 4 , wherein said reading position setting unit outputs an error signal when the maximum value of the electric signal output by said photoelectronic converter is equal to or less than the predetermined value.
6. The apparatus according to claim 1 , wherein said reading position setting unit sets the reading position when the range in the sub-scan direction over which the predetermined threshold value is exceeded is broader than a predetermined range.
7. The apparatus according to claim 6 , wherein said reading position setting unit outputs an error signal when the range in the sub-scan direction over which the predetermined threshold value is exceeded is narrower than the predetermined range.
8. The apparatus according to claim 1 , wherein said reading position setting unit controls to perform a pre-processing of moving said document reading unit, causing the photoelectronic converter to output an electric signal at each position to which the document reading unit is moved, and detecting a position in the sub-scan direction that corresponds to the maximum value of this electric signal, and to execute processing for setting the reading position with regard to a predetermined range the center of which is the position in the sub-scan direction obtained in the pre-processing.
9. An image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is sensed by the document reading unit to thereby read an image on the document, said apparatus comprising: a photoelectronic converter for outputting an electric signal that conforms to amount of incident light; and a reading position setting unit adapted to move the document reading unit, irradiating the feed roller with light from the light source at each position to which the document reading unit is moved, cause said photoelectronic converter to output an electric signal that conforms to amount of light reflected from the feed roller at each position, detect a range in a sub-scan direction over which this electric signal exceeds a predetermined threshold value, detect a flat portion of the read signal within this range, and set the center of the detected flat portion as a reading position.
10. The apparatus according to claim 9 , wherein said reading position setting unit decides the threshold value based upon a maximum value of the electric signal output by said photoelectronic converter.
11. The apparatus according to claim 10 , wherein said reading position setting unit adopts a value, which is obtained by multiplying the maximum value of the electric signal output by said photoelectronic converter by a predetermined coefficient, as the threshold value.
12. The apparatus according to claim 10 , wherein said reading position setting unit decides the threshold value based upon the maximum value of the electric signal, which is output by said photoelectronic converter, when said maximum value is greater than a predetermined value.
13. The apparatus according to claim 12 , wherein said reading position setting unit outputs an error signal when the maximum value of the electric signal output by said photoelectronic converter is equal to or less than the predetermined value.
14. The apparatus according to claim 9 , wherein said reading position setting unit sets the reading position when the range in the sub-scan direction over which the predetermined threshold value is exceeded is broader than a predetermined range.
15. The apparatus according to claim 14 , wherein said reading position setting unit outputs an error signal when the range in the sub-scan direction over which the predetermined threshold value is exceeded is narrower than the predetermined range.
16. The apparatus according to claim 9 , wherein said reading position setting unit controls to perform a pre-processing of moving said document reading unit, causing the photoelectronic converter to output an electric signal at each position to which the document reading unit is moved, and detecting a position in the sub-scan direction that corresponds to the maximum value of this electric signal, and to execute processing for setting the reading position with regard to a predetermined range the center of which is the position in the sub-scan direction obtained in the pre-processing.
17. A reading position setting method in an image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is converted to an electric signal by a photoelectronic converter to thereby read an image on the document, said method comprising: a read-out step of moving the document reading unit, irradiating the feed roller with light from the light source at each position to which the document reading unit is moved and causing said photoelectronic converter to output an electric signal that conforms to amount of light reflected from the feed roller at each position; a detection step of detecting a range in a sub-scan direction over which the electric signal exceeds a predetermined threshold value; and a setting step of setting a position at the center of the range, which has been detected at said detection step, as a reading position.
18. The method according to claim 17 , wherein the threshold value is decided based upon a maximum value of the electric signal output by the photoelectronic converter.
19. The method according to claim 18 , wherein a value, which is obtained by multiplying the maximum value of the electric signal output by the photoelectronic converter by a predetermined coefficient, is adopted as the threshold value.
20. The method according to claim 18 , wherein the threshold value is decided based upon the maximum value of the electric signal, which is output by the photoelectronic converter, when said maximum value is greater than a predetermined value.
21. The method according to claim 20 , further comprising a step of outputting an error signal when the maximum value of the electric signal output by the photoelectronic converter is equal to or less than the predetermined value.
22. The method according to claim 17 , wherein the reading position is set at said setting step when the range in the sub-scan direction over which the predetermined threshold value is exceeded is broader than a predetermined range.
23. The method according to claim 22 , further comprising a step of outputting an error signal when the range in the sub-scan direction over which the predetermined threshold value is exceeded is narrower than the predetermined range.
24. The method according to claim 17 , further comprising the following steps executed before said read-out step: a step of moving said document reading unit and causing the photoelectronic converter to output an electric signal at each position to which the document reading unit is moved; and a step of detecting a position in the sub-scan direction that corresponds to the maximum value of this electric signal; wherein processing is executed at said read-out step with regard to a predetermined range the center of which is the obtained position in the sub-scan direction.
25. A reading position setting method in an image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is converted to an electric signal by a photoelectronic converter to thereby read an image on the document, said method comprising: a read-out step of moving the document reading unit, irradiating the feed roller with light from the light source at each position to which the document reading unit is moved and causing said photoelectronic converter to output an electric signal that conforms to amount of light reflected from the feed roller at each position; a first detection step of detecting a range in a sub-scan direction over which the electric signal exceeds a predetermined threshold value; a second detection step of detecting a flat portion of the read signal within the range detected at said first detection step; and a setting step of setting the center of the flat portion, which has been detected at said second detection step, as a reading position.
26. The method according to claim 25 , wherein the threshold value is decided based upon a maximum value of the electric signal output by the photoelectronic converter.
27. The method according to claim 26 , wherein a value, which is obtained by multiplying the maximum value of the electric signal output by the photoelectronic converter by a predetermined coefficient, is adopted as the threshold value.
28. The method according to claim 26 , wherein the threshold value is decided based upon the maximum value of the electric signal, which is output by the photoelectronic converter, when said maximum value is greater than a predetermined value.
29. The method according to claim 28 , further comprising a step of outputting an error signal when the maximum value of the electric signal output by the photoelectronic converter is equal to or less than the predetermined value.
30. The method according to claim 25 , wherein the reading position is set at said setting step when the range in the sub-scan direction over which the predetermined threshold value is exceeded is broader than a predetermined range.
31. The method according to claim 30 , further comprising a step of outputting an error signal when the range in the sub-scan direction over which the predetermined threshold value is exceeded is narrower than the predetermined range.
32. The method according to claim 25 , further comprising the following steps executed before said read-out step: a step of moving said document reading unit and causing the photoelectronic converter to output an electric signal at each position to which the document reading unit is moved; and a step of detecting a position in the sub-scan direction that corresponds to the maximum value of this electric signal; wherein processing is executed at said read-out step with regard to a predetermined range the center of which is the obtained position in the sub-scan direction.
33. A computer program product comprising a computer-usable medium having computer-readable program code means embodied in said medium for a reading position setting method in an image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is converted to an electric signal by a photoelectronic converter to thereby read an image on the document, said product including: first computer-readable program code means for moving the document reading unit, irradiating the feed roller with light from the light source at each position to which the document reading unit is moved and causing said photoelectronic converter to output an electric signal that conforms to amount of light reflected from the feed roller at each position; second computer-readable program code means for detecting a range in a sub-scan direction over which the electric signal exceeds a predetermined threshold value; and third computer-readable program code means for setting a position at the center of the detected range as a reading position.
34. A computer program product comprising a computer-usable medium having computer-readable program code means embodied in said medium for a reading position setting method in an image reading apparatus for moving a document reading unit to a point below a document feeder that feeds documents, and emitting light from a light source of the document reading unit toward a feed roller of the document feeder, whereby light reflected from a document that travels between the feed roller and the light source is converted to an electric signal by a photoelectronic converter to thereby read an image on the document, said product including: first computer-readable program code means for moving the document reading unit, irradiating the feed roller with light from the light source at each position to which the document reading unit is moved and causing said photoelectronic converter to output an electric signal that conforms to amount of light reflected from the feed roller at each position; second computer-readable program code means for detecting a range in a sub-scan direction over which the electric signal exceeds a predetermined threshold value; third computer-readable program code means for detecting a flat portion of the read signal within the detected range; and fourth computer-readable program code means for setting the center of the detected flat portion as a reading position.
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December 3, 2001
January 31, 2006
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